1. Field of the Invention
The present invention relates to a coupling device, and in particular relates to a coupling device providing dual-band and dual-perpendicular-polarization functions.
2. Description of the Related Art
FIG. 1 shows a conventional coupling antenna 1, comprising a substrate 10, a ground element 20, a first feed conductor 30 and a second feed conductor 40. The substrate 10 comprises a first surface 11 and a second surface 12. The ground element 20 is disposed on the second surface 12, comprising a first portion 21, a second portion 22 and an annular groove 23. The annular groove 23 is located between the first portion 21 and the second portion 22. The first feed conductor 30 is disposed on the first surface 11 corresponding to the first portion 21 and the annular groove 23. The second feed conductor 40 is disposed on the first surface 11 corresponding to the first portion 21 and the annular groove 23.
When the conventional coupling antenna 1 transmits wireless signals, the signal isolation between the first feed conductor 30 and the second feed conductor 40 is insufficient, and noise is generated therebetween. Additionally, the conventional coupling antenna 1 can only transmit signals in a single band, which cannot satisfy multi-band signal transmission requirements.